Auto stabilised gas burner

ABSTRACT

The specification discloses an auto-stabilised gas burner which has a burner head defining a distribution chamber and comprising a series of vertical slots. At their upper part, the slots have a preferential flow zone produced by means of waisting formed by a shaped portion of the burner head and the lower face of a deflector.

United States'Patent 1191 8/1962 France 431/349 11] 3,820,945 Vignes June 28, 1974 [54] AUTO-STABILISED GAS-BURNER 1,288,154 2/1962 France 431/349 Inventor: ogg gn Paris France 1,327,885 4/1963 France 431/349 [73] Afsslgmel Gal De France Pans France 0 Primary Examiner-Carroll B. Dority, Jr. Flledl 1972 Attorney, Agent, or Firm-Eyre, Mann & Lucas [21] Appl, No.: 308,809

[30] Foreign Application Priority Data [57] ABSTRACT Nov. 23, 1971 France 71.41876 The specification discloses an autostabilised gas burner which has a burner head defining a distribution [52] US. Cl. 431/349, 239/568 chamber and Comprising a Series of Vertical Slots At [51] Int. Cl. F2311 13/36 their upper part the Slots have a preferential flow [58] Field of Search 239/568; 431/349 Zone produced by means of i i formal by a shaped portion of the burner head and the lower face [56] References Cited f a deflector FOREIGN PATENTS OR APPLICATIONS 1,304,720 3 Claims, 2 Drawing Figures 1 AUTO -STABILISED GAS-BURNER The present invention relates to an auto-stabilised burner using gaseous fuel and capable of having the flame retracted within the burner head.

It is known to connect the burner head to a distribution chamber and for the burner head to comprise a series of substantially vertical narrow slots which have at their upper part a preferential flow zone'for the air/gas mixture, this preferential flow zone being a zone in which the pressure drop is very small relative to adjacent zones and being produced by means of a waisting formed in the burner head at the outer face of the latter.

Due to the existence of the preferential flow zones of the slots, these being zones in which the flame gathers under low operating conditions, such burners are capable of operating with a. good heat yield when throttled down to very low operating conditions and also when turned up to very highoperating conditions, the ratio between these extreme operating conditions being approximately lz20.

However, in known burners of this type, the deflector is situated at a certain spacing above the waisting so that under low operating conditions when the flame has been retracted into the waisting the flame is spaced from the deflector and this results in appreciable heat losses. Furthermore, in these known burners the distribution chamber is located below the burner head and consequently, the said distribution chamber and the burner head cannot be produced in a single piece.

It isan object of the invention to overcome these disadvantages and especially to provide a burner of the abovementioned type which is very simple to construct and assemble.

According to the present invention there is provided in an auto-stabilised burner including a distribution chamber for air-fuel mixture a burner head comprising: a series of substantially vertical narrow slots; aperture means in said slots defining waisting formed in the outer face of the burner head; a deflector which overlies at least a part of said aperture of each slot and a base which defines the lower end of the slots and has a rim which projects slightly outwards beyond the bases of the slots, the. improvement wherein the distribution chamber is. located in the burner headand that the upper end of the burner head is cut away to leave a channel which, together with the lower face of said deflector, forms the waisting of the burner head.

Thus when the burner. of this invention is used under low operating conditions the flame remains in the immediate vicinity of the deflector, that is to say of the products to be heated, so that the heat from the said flame, is used with maximum yield. Furthermore, the deflector is now used to form a part of the waisting of the burner head, so that the said waisting can be machined more easily.

The deflector preferably overhangs considerably beyond the waisting of the burner head and overlies at least a part of the zone of the said burner head which is situated outside the waisting.

' The deflector advantageously has a recess or shoulder of suitable shape machined in its lower face, into which the upper end of the burner head can be fitted with a very small amount of play. This latter characteristic makes it possible to simplify the construction of the deflector and to mount it on the burner head.

It is advantageous to make the cross-section of the wall of the burner head of substantially trapezoidal shape when viewed in a plane perpendicular to the deflector, the long base of the trapezoid facing the bottom. In this way, the vertical slots which are formed in the wallof the burner head give a gradually decreasing pressure dropas a function of the height. The advantage of this latter characteristic: is especially that it makes itpossible to contract the flame gradually into the waisting when the supply pressure of the air/gas mixture decreases.

I In order that thepresent invention may be better understood the following description is given, merely by way of example, reference being made to the accompanying drawing in which:

FIG. 1 is a horizontal cross-section taken along the line I-I of FIG. 2, and shows a burner according to the invention; and I FIG. 2 is a transverse cross-section taken along the line lI-II of FIG. 1.

The burner illustrated in FIGS. 1 and 2 includes a burner head 1, in the present case of annular shape, which has its lower part in the shape of a cylindrical base 2 resting on the surface of a'cooker 3. The upper face of the burner head 1 is provided with a series of narrow radially extending vertical slots 4 distributed around the periphery of the burner head 1. As is known each of the slots 4 has, at its upper end, a preferential flow zone 4a in which the pressure drop is very small relative to the adjacent z'ones. This preferential flow zone 4a is produced for each slot by means of waisting in the burner head, in the form of an annular space 5, machined in the burner head 1 from the outer face of the latter. The upper part of the base 2 defines the lower extremities of the slots 4 and has an annular rim 6 which projects slightly radially outwardly beyond the bases of the slots 4. The burner also contains a deflector plate 7 which overhangs the upper part of the aper ture of the slots 4 and is mounteddirectly on the burner head 1. I

The central part of the base 2 has an axial cylindrical bore 8 passing through it, which defines a recess to receive a vertical rigid guide sleeve 9 attached to the surface of the cooker 3. The sleeve 9 fits in the recess with a very small amount of play and forms one end of a supply pipeline 9a, which extends beyond the surface of I the cooker 3 and has its other end connected to a mixer (not shown) for the combustible gas and air.

As can be seen more clearly in FIG. 2, the burner head 1 together with the deflector plate 7 defines a distribution chamber 10 into which the supply pipeline opens directly to supply the fuel mixture. Moreover the annular waisting 5 of the burner head 1 is defined, on the one hand, by an annular peripheral zone 7a of the lower face of the deflector 7, and on the other hand, by an annular recess consisting of a shaped cut-away portion 11 machined from the outer peripheral face of each slot 4 defining the otherwise truncated cone shape 1a of the burner head 1. In the present case, the annular recess 11 is defined on the periphery la by a horizontal cut 11a and a vertical cut 11b. As can be seen on FIG. 2, the deflector 7 overhangs the annular waisting 5, and also overlies the upper face of the burner head 1 at least to a considerable extent.

On its lower face, the deflector plate 7 is equipped with a central cylindrical recess the periphery of which forms a low annular shoulder 12, into which fits the generally cylindrical upper end lb of the burner head 1, with a very small amount of play.

As shown in FIG. 2, the wall of the burner head 1 has a substantially trapezoidal shape the long base of which faces the bottom when the burner is viewed in transverse cross-section and, in the present case, in radial cross-section.

The illustrated burner thus has a retractable flame and can be fitted onto standard cooker surfaces. It consists essetially of two parts which are simple to make and which can be mounted onto one another and onto the surface of such a standard cooker by simply push fitting the parts into one another.

Of course, the general shape of the burner head 1 can be other than circular in plan view. The burner head 1 can for example be of a generally elongated oval or rectangular shape.

This burner operates in the same way as known burners with retractable flame. Under normal or strong operating conditions an annular flame is obtained such as that shown in FIG. 2 as comprising a region of blue flame 13 and a plume 14. The secondary air travels along the direction of the arrow f, and, due to the annular rim 6 of the cylindrical base 2, is slightly deviated towards the upper part 14 of the flame to contribute towards making the flame more upright at the top. When the burner is throttled down, the flame gradually becomes concentrated or gathers together until under very low operating conditions it occupies only the volume of the annular waisting 5 and the flame thus has a very low heat output and is in the shape of a thin ring.

I claim:

1. In an auto stabilizer burner, a burner head comprising a base, said base being recessed inwardly at its lower end to define a flat rim and including a side wall having a portion inclined inwardly of said burner and beginning at said rim, said side wall being cut away at an end opposite said rim to define a shoulder substantially parallel with said rim, a plurality of spaced slots extending completely through said side wall and extending substantially from said rim to the end of said side wall opposite said rim, a distribution chamber formed within said burner head, a deflector positioned over one end of said distribution chamber and having an undersruface mating with said side wall and being substantially parallel to said shoulder and extending outwardly beyond said shoulder to define a channel.

2. The improvement according to claim 1, and wherein said deflector comprises a shoulder operative to engage said side wall.

3. The improvement according to claim 1, and wherein said deflector comprises means defining a recess operative to engage said side wall therein. 

1. In an auto stabilizer burner, a burner head comprising a base, said base being recessed inwardly at its lower end to define a flat rim and including a side wall having a portion inclined inwardly of said burner and beginning at said rim, said side wall being cut away at an end opposite said rim to define a shoulder substantially parallel with said rim, a plurality of spaced slots extending completely through said side wall and extending substantially from said rim to the end of said side wall opposite said rim, a distribution chamber formed within said burner head, a deflector positioned over one end of said distribution chamber and having an undersruface mating with said side wall and being substantially parallel to said shoulder and extending outwardly beyond said shoulder to define a channel.
 2. The improvement according to claim 1, and wherein said deflector comprises a shoulder operative to engage said side wall.
 3. The improvement according to claim 1, and wherein said deflector comprises means defining a recess operative to engage said side wall therein. 